Cell size

Watch this video about what governs the size of a cell. How big can a single cell be?

Range of structure sizes and how we can see them. For example, mitochondrion and bacteria are about the same size (1 micrometer length) and can be seen using electron and light microscope.

Modern compound microscope

Compound Light Microscope
Compound Light Microscope.

Unlike van Leeuwenhoek’s single lens microscope, we now combine the magnifying power of multiple lenses in what is called a compound microscope.

Electron microscopy

Schematic of Transmitting Electron Microscope.

An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination.

Scanning and transmission electron microscope has magnifications of up to about 10,000,000x whereas most light microscopes have a limit of magnifications below 2000x

Scanning electron microscope (SEM) shows pictures of structures in 3D while transmission electron microscope (TEM) gives pictures of structures in 2D.

TEM image of cross section of mammalian lung showing two mitochondria. Observe the cristae made by the convolution of the inner membrane.
SEM of human blood with concave red blood cells and spherical white blood cells.

Fluorescent microscopy

Schematic of a fluorescent microscope.
  • Antibodies developed against a specific protein
    • Fluorescent dye molecule attached to antibody molecules
  • Specimen exposed to fluorescent antibodies
  • Ultra-violet light (black light) passed through specimen
    • Fluorescent dye glows in color where antigen is located
  • Emitted light is focused by glass lenses onto human retina or camera
    • Allows mapping distribution of a specific protein in cell
Fluorescent Microscope.
Light micrograph overlayed with a fluorescent micrograph of green fluorescent protein expressing cells.

Dissecting microscope

Dissecting microscope.

Dissecting microscope allow to visualize organisms or bacterial colonies at low magnification.

It was primarily used to see more details while perform dissections.